Strain-Controlled High Mobility in Modulation Doped Si0.5Ge0.5/Ge/Si1-xGex Hetero-Structures

1989 ◽  
Vol 160 ◽  
Author(s):  
Masanobu Miyao ◽  
Eiichi Murakami ◽  
Hiroyuki Etoh ◽  
Kiyokazu Nakagawa
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Valence Band ◽  
Strain Field ◽  
High Mobility ◽  
Buffer Layers ◽  
Two Dimensional ◽  
Mbe Growth ◽  
Hetero Structure

AbstractFormation and characterization of a new hetero -structure of modulation doped p-Si0.5Ge0.5/Ge/Si1-xGex are comprehensively studied. In the MBE growth, thick Si1-xGex buffer layers are grown incommensurately at high temperature (520°C), and thin Si0.5Ge0.5/Ge layers are grown commensurately at low temperature (≦450°C). The strain field in the Ge channel layers can be precisely controlled by changing the Si composition (1-X) in the Si 1 -xGex buffer layers. As a result, a large energy discontinuity in the valence band (0.17 eV) is realized at the hetero -interface of p-Si0.5Ge0.5/Ge. This enables a high mobility of two -dimensional hole gas (4500 cm2/Vs) at 77 K.

Synthesis and Characterization of Aerogel-derived Cation-substituted Hexaaluminates

1996 ◽  
Vol 457 ◽  
Author(s):  
Lin-chiuan Yan ◽  
Levi T. Thompson
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Catalytic Combustion ◽  
High Surface ◽  
High Surface Area ◽  
Synthesis And Characterization ◽  
New Methods ◽  
Surface Areas ◽  
Different Characteristics

ABSTRACTNew methods have been developed for the synthesis of high surface area cation-substituted hexaaluminates. These materials were prepared by calcining high temperature (ethanol extraction) or low temperature (CO2 extraction) aerogels at temperatures up to 1600°C. Cation-substituted hexaaluminates have emerged as promising catalysts for use in high temperature catalytic combustion. In comparing unsubstituted and cation-substituted hexaaluminates, we found that the phase transformations were much cleaner for the cation-substituted materials. BaCO3 and BaAl2O4 were intermediates during transformation of the unsubstituted materials, while the cation-substituted materials transformed directly from an amorphous phase to crystalline hexaaluminate. Moreover, the presence of substitution cations caused the transformation to occur at lower temperatures. Mn seems to be a better substitution cation than Co since the Mn-substituted materials exhibited higher surface areas and better heat resistances than the Co-substituted materials. The low temperature aerogel-derived materials possessed quite different characteristics from the high temperature aerogel-derived materials. For example, phase transformation pathways were different.

HIGH Tc SUPERCONDUCTIVITY: A MODEL BASED ON ANTIFERROMAGNETIC FLUCTUATIONS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 1089-1096
Author(s):  
D. Schmeltzer
Keyword(s):  
Free Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Fermi Liquid ◽  
Antiferromagnetic Interaction ◽  
Two Dimensional ◽  
Fractional Statistics ◽  
Bose Statistic ◽  
High Tc ◽  
High Tc Superconductivity

The system X–La–Cu–O is described as a Fermi liquid with antiferromagnetic interaction. This interaction gives rise to two types of fluctuations, magnetic and superconducting. As a result, we find a free energy which contains two order parameters which at high temperature give rise to superconductivity and at low temperature to reentry-like paramagnetism. For two-dimensional systems, topological effects give rise to fractional statistics and as a result superconductivity appears when the topological angle θ gives rise to a Bose statistic.

Characterization of the melting behavior of high-temperature and low-temperature ashes

2015 ◽  
Vol 134 ◽  
pp. 441-448 ◽  
Author(s):  
Jie Xu ◽  
Feng Zhao ◽  
Qinghua Guo ◽  
Guangsuo Yu ◽  
Xia Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Melting Behavior

Characterization of mismatched SiGe grown on low temperature Si buffer layers by molecular beam epitaxy

1997 ◽  
Vol 175-176 ◽  
pp. 499-503 ◽  
Author(s):  
K.K. Linder ◽  
F.C. Zhang ◽  
J.-S. Rieh ◽  
P. Bhattacharya
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Buffer Layers
Sign in / Sign up

Export Citation Format

Share Document